You can manage your voicemail options online with the Web Phone Manager.

Web PhoneManager allows users to manage their mailbox recordings and their mailbox settings. Web Phone Manager provides a convenient graphical user interface and a system of tabs that organizes messages and mailbox settings that allows users quick and easy access to their mailbox. If you cannot remember your security code or your mailbox number, you can use the security code reset feature of Web PhoneManager to reset it.

Initial mail box set up must be completed before this option is available.Instructions here.